1. Field of the Invention
The present invention relates to a hydraulic pressure warning system for an internal combustion engine equipped with a hydraulic pressure sensor.
2. Description of Background Art
An internal combustion engine is known wherein a hydraulic pressure sensor for detecting the hydraulic pressure of lubricating oil is installed in an oil passage inside a crankcase sidewall and on the downstream side of and in proximity to an oil pump. See, for example, Japanese Patent Laid-open No. 2006-283567. In addition, a hydraulic pressure warning system is know that is adapted to warn of the lowering of hydraulic pressure of the lubricating oil of the internal combustion engine on the basis of the detection of a hydraulic pressure sensor. See, for example, Japanese Patent Laid-open No. Hei 8-312507.
In addition, the internal combustion engine described in Japanese Patent Laid-open No. 2006-283567 has the hydraulic pressure sensor directly attached thereto. Therefore, the hydraulic pressure sensor may probably be influenced by heat radiated from the internal combustion engine. The hydraulic pressure sensor described in Japanese Patent Laid-open No. 2006-283567 is installed in the oil passage on the downstream side of and in proximity to the oil pump. More specifically, the sensor is located close to the oil pump. Therefore, the hydraulic pressure sensor tends to be influenced by the pulsation of the oil pump. Thus, like the hydraulic pressure warning system described in Japanese Patent Laid-open No. Hei 8-312507, when a warning is about to be given the lowering of the hydraulic pressure based on the detection of the hydraulic pressure sensor, it may probably not be given in an appropriate manner.